998 resultados para Lê numbers
Resumo:
We write down the renormalization-group equations for the Yukawa-coupling matrices in a general multi-Higgs-doublet model. We then assume that the matrices of the Yukawa couplings of the various Higgs doublets to right-handed fermions of fixed quantum numbers are all proportional to each other. We demonstrate that, in the case of the two-Higgs-doublet model, this proportionality is preserved by the renormalization-group running only in the cases of the standard type-I, II, X, and Y models. We furthermore show that a similar result holds even when there are more than two Higgs doublets: the Yukawa-coupling matrices to fermions of a given electric charge remain proportional under the renormalization-group running if and only if there is a basis for the Higgs doublets in which all the fermions of a given electric charge couple to only one Higgs doublet.
Resumo:
Foram mostrados alguns aspectos sobre a ecologia de 11 espécies de Culicidae que procriam em recipientes, em uma área urbana do Sul do Brasil. Os mais variados tipos de recipientes foram listados como eficientes criadouros para larvas de culicídeos. Aedes aegypti apareceu como espécie recém-introduzida e limitada somente a duas áreas da cidade. As espécies predominantes foram: Culex quinquefasciatus, Culex coronator, Aedes aegypti, Aedes fluviatilis e Limatus durhamii.
Resumo:
BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) letswaart collected from three localities of north Tunisia - Krib, Bargou and Nefza - were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin-Ciocalteu method, and antioxidant effectiveness, using the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p-cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), gamma-terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC50, ranged from 59 to 80 mg L-1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg(-1) dry weight, varied from 9.37 to 17.70 g kg(-1) dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p-cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated.
Resumo:
The modelling of the experimental data of the extraction of the volatile oil from six aromatic plants (coriander, fennel, savoury, winter savoury, cotton lavender and thyme) was performed using five mathematical models, based on differential mass balances. In all cases the extraction was internal diffusion controlled and the internal mass transfer coefficienty (k(s)) have been found to change with pressure, temperature and particle size. For fennel, savoury and cotton lavender, the external mass transfer and the equilibrium phase also influenced the second extraction period, since k(s) changed with the tested flow rates. In general, the axial dispersion coefficient could be neglected for the conditions studied, since Peclet numbers were high. On the other hand, the solute-matrix interaction had to be considered in order to ensure a satisfactory description of the experimental data.
Resumo:
Results obtained with catches performed at several sites of the Ribeira Valley, SP (Brazil) are reported. Collections with Shannon type traps showed a concentration of An.albitarsis s.l. in the Experimental Farm of Pariquera-Açu County, associated with the development of irrigated rice cultivation. Two species of the complex, named A and B, were recognized. Species B predominated in the samples. Indoor and outdoor crepuscular human bait captures were performed a the domiciliary environment. The two species showed a generally low William's media valve of 0.2, the highest value obtained was 1.6. No differences were found between indoor and outdoor behaviours between the two species of the complex.
Resumo:
Objetivando-se conhecer as espécies de Culicidae aptas a colonizarem ambiente de um ribeirão com mata ciliar reduzida e localizado na região Sul do Brasil, foram realizadas capturas com auxílio de rede para coleta de insetos aquáticos. Foram apanhadas as seguintes espécies: Aedes crinifer, Aedomya squamipennis, Anopheles fluminensis, An. intermedius, An. albitarsis, An. argyritarsis, An. evansae, An. galvaoi, An. oswaldoi, An. strodei, An. triannulatus, Chagasia fajardi, Culex bidens, Cx. grupo coronator, Cx. eduardoi, Cx. mollis, Cx. quinquefasciatus, Cx. coppenamensis, Cx. vaxus, Cx. grupo inhibitator, Cx. intrincatus, Cx. (Melanoconion) sp., Psorophora saeva (?) e Uranotaenia pulcherrima. Para as espécies em que foi capturada uma amostra tida como representativa, foram estudadas a distribuição ao longo da área pesquisada, a flutuação populacional e a correlação com fatores físicos do ambiente. Conclui-se da análise que massas de água orladas por mata ciliar reduzida podem funcionar como refúgio para alguns Culicidae e esta condição pode contribuir decisivamente para o processo de domiciliação de espécies deste grupo.
Resumo:
The study’s main purpose was the assessment of the environmental fungal contamination, the exploration of possible associations between related environmental variables and the study of the relationship between fungal contamination of air and surfaces. A descriptive study was developed based upon air and surfaces monitoring for fungal contamination in ten indoor gymnasiums with a swimming pool located in Lisbon’s urban area. Fifty 200 litres air samples and 120 surface swabs were collected. Surfaces samples were collected before and after cleaning and disinfection and temperature and relative humidity values were registered during the collection period. Twenty five different species of fungi were identified in the air samples, being the three most commonly isolated genera the following: Cladosporium (36.6%), Penicillium (19.0%) and Aspergillus (10.2%). Thirty-seven different species of fungi were identified in the surface samples. Fusarium sp. was the most frequent genera before (19.1%) and after (17.2%) cleaning and disinfection. There was a significant association between the numbers of visitors and the fungal contamination determined in the surface samples (p<0.05). There was no significant association (p>0.05) between the contamination encountered in the air samples and the one registered in the surface samples and between the fungal contamination and the temperature or relative humidity measured on location. The data obtained enabled the assessment of the establishment’s fungal contamination and led the authors to conclude, consequently, that physical activity, which generally promotes health, can in fact be challenged by this factor.
Resumo:
A descriptive study was developed to compare air and surfaces fungal contamination in ten hospitals’ food units and two food units from companies. Fifty air samples of 250 litres through impaction method were collected from hospitals’ food units and 41 swab samples from surfaces were also collected, using a 10 by 10 cm square stencil. Regarding the two companies, ten air samples and eight surface samples were collected. Air and surface samples were collected in food storage facilities, kitchen, food plating and canteen. Outdoor air was also collected since this is the place regarded as a reference. Simultaneously, temperature, relative humidity and meal numbers were registered. Concerning air from hospitals’ food units, 32 fungal species were identified, being the two most commonly isolated genera Penicillium sp.
Resumo:
Se evidencia la presencia de promastigotos metacíclicos de Leishmania pifanoi en el conducto hipofaríngeo de Lutzomyia youngi infectados experimentalmente por ingurgitación sobre lesiones tarsales de hámsteres. La aparición de metacíclicos en la hipofaringe, cuya morfología se ilustra, ocurre entre los 5 y 9 días de desarrollo postprandial y es más frecuente en insectos alimentados con sacarosa comercial no refinada. Se investiga el papel de derivados aminados de glucosa y galactosa y también de aminoácidos, en la promoción y migración de los metacíclicos.
Resumo:
Results obtained with Anopheles albitarsis s.l. catches mainly performed through human bait at the Ribeira Valley region, SP (Brazil), are reported. Two species of the complex were recognized, namely An. albitarsis s.s. and species B. This latter predominated both in the rice fields and in the dwelling environments. The crepuscular rhythms showed an unimodal sunset pattern with most blood-seeking females caught during dusk. The absence of differences between indoor and outdoor behavior was confirmed for both species of the complex.
Resumo:
INTRODUCCIÓN: La Fasciolosis constituye en diversas regiones una fuente importante de pérdidas económicas y cuando se descuidan las medidas de control de sus hospedadores (moluscos), junto a condiciones ecológicas favorables, pueden ocurrir casos aislados de Fasciolosis humana. Dentro de los métodos alternativos para su control está el uso de extractos vegetales y se pretendió evaluar el probable empleo del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L.) en el control de Lymnaea cubensis, principal vector de la Fasciolosis en Cuba. MATERIAL Y MÉTODO: Diferentes concentraciones del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L.) fueron testados para determinar las dosis letales media (DL50) y máxima (DL90) usando un programa computarizado Probit-Log. Siete series experimentales fueron probadas usando 72 moluscos en cada una. Para determinar la influencia sobre la frecuencia cardíaca fueron testados tres grupos de 10 moluscos, dos fueron tratados con las DL50=0,88627 y DL90=1,7641, respectivamente, mientras que el tercero fue considerado como testigo. RESULTADOS Y CONCLUSIONES: Se observó una marcada influencia de ambas dosis sobre la frecuencia cardíaca del molusco estudiado. Estos resultados son alentadores, pues demuestran el potencial empleo de esta planta en el control de moluscos indeseables.